The principal objective of this research is to develop convenient and selective chemical liquid chromatographic procedures to separate, characterize and determine various classes of compounds which could serve as potentially useful clinical and biochemical markers in uremia and chronic renal failure, and which may be significant in associated disease states. We have recently developed selective liquid chromatographic procedures to analyze for guanidino compounds and polyamines. Both of these methods utilize ion-pairing chromatographic techniques and selective on-line post-column reaction detector systems. A detailed study of vitamin loss for patients on hemodialysis was also completed recently. During the coming year, it is planned to continue this work by conducting extensive clinical screening programs for guanidine and polyamine levels in uremic hemodialysate, serum and other physiological fluids. Additional studies will be conducted on two other classes of compounds: middle molecular weight molecules (polypeptide fragments) and tryptophan and its metabolites. All of these compounds can be separated by liquid chromatography and can be detected in trace quantities. Peak identification will be accomplished by mass spectrometry.